The ultimate goal of our research is to develop elastography systems for simple hand-held operation compatible with transrectal examinations of prostate. Ultrasonic elastography senses internal deformations (strains) induced by external compression. It forms cross-sectional images that map the internal tissue deformation. Current techniques have shown great potential, especially for diagnosing hard cancerous structures. However, current systems require large mechanical applicators and are restricted to examinations of external organs, such as the breast. We have identified mechanical-applicator strategies and a hierarchy of signal-processing concepts that promise to overcome current limitations of freehand elastography for diagnostic cancer imaging; they would permit practical handheld operation using small mechanical assemblies that are well suited for transrectal imaging of prostate and rectal cancers. Our concepts promise a substantial impact on cancer imaging, but they must be considered "high risk" research because they address complex issues and their feasibility is not yet proven. This two-year development program is designed to test the feasibility of the methods, to make informed judgements as to ultimate utility, and to identify problem areas requiring further investigation. First, we will explore data acquisition methods that limit undesirable motion between successive data acquisition steps, and mechanical devices that promise to minimize undesirable motion in handheld applications. Each device will be tested in phantoms and in-vitro preparations. Second, we will investigate and test a hierarchy of increasingly complex strain estimation approaches to deal with increasing undesirable tissue motions. Third, to help validate our concepts, we will acquire data from a small patient population being treated for prostate cancer at the New York Columbia Presbyterian Medical Center using commercial transrectal scanners that we have already interfaced for digital data acquisition for current, ongoing collaborative studies. If this exploratory research demonstrates the feasibility of our concepts, we will employ our results to formulate a systematic development and clinical evaluation program suitable for a comprehensive R01 research grant.